In recent years it has become increasingly apparent that the phenomena of repetition priming is not a unitary concept. Investigators of normal memory have been able to demonstrate that both a perceptual component and a conceptual component contribute to the phenomena of enhanced performance when stimuli are repeated during a task. Depending upon the demands of the experiment, or the instructions that are given, one of these components might be emphasized, or depended upon, more than the other. It is expected, from several preliminary studies, that the "normal" priming of amnesics is more dependent upon perceptual characteristics than upon conceptual. Whether this represents an activation of structural representation or the fluency produced by normal priming of visual stimuli remains to be investigated. In order to explore the parameters of this phenomena, the experiments in the present component are designed. The first series of experiments seeks to explore the range of perceptual processes contributing to perceptual priming that may, or may not, be intact in amnesia. Stimuli varying in size, color and orientation will be utilized for their priming capabilities in both a memory impaired and a control population. It is anticipated that amnesic patients will be normally sensitive to these stimulus attributes on a variety of testing paradigms including object decision, object identification, and object completion. Using both common objects and novel objects as stimuli, a second series of tasks is designed to examine perceptual learning across multiple trials for amnesics. The purpose of these studies is to determine whether new perceptual learning skills can be acquired by memory disordered patients by building upon their normal perceptual priming abilities. Theoretically, additions to their perceptual structural representations could be made during the learning of orientation invariance and mental rotation tasks. The final set of experiments will explore the basic parsing skills of amnesics during tasks that require organization of visual information. Similar "manipulative" skills are seen as impaired in verbal analysis by amnesics, but perceptual classification skills have not yet been investigated. The nature of this form of perceptual learning will be explored through the use of paradigms that require the patient to impose some form of organization on a visual display in order to perceive its inherent characteristics.